Hartzell HC-E4 3 Series Owner's Manual page 4

Propeller Owner's Manual
147
WARNING
(Rev. 2)
People who fly should recognize that various types of
risks are involved; and they should take all precautions to
minimize them, since they cannot be eliminated entirely.
The propeller is a vital component of the aircraft. A
mechanical failure of the propeller could cause a forced
landing or create vibrations sufficiently severe to damage
the aircraft, possibly causing it to become uncontrollable.
Propellers are subject to constant vibration stresses
from the engine and airstream, which are added to high
bending and centrifugal stresses.
Before a propeller is certified as being safe to operate
on an airplane, an adequate margin of safety must be
demonstrated. Even though every precaution is taken in
the design and manufacture of a propeller, history has
revealed rare instances of failures, particularly of the
fatigue type.
It is essential that the propeller is properly maintained
according to the recommended service procedures and
a close watch is exercised to detect impending problems
before they become serious. Any grease or oil leakage,
loss of air pressure, unusual vibration, or unusual
operation should be investigated and repaired, as it could
be a warning that something serious is wrong.
Page 2
61-00-47
MESSAGE
Rev. 17 Sep/20